A perturbation calculation shows that the power spectrum of strange attractor near the accumulation parameter of a period-doubling bifurcation sequence consists of peaks broadened by a phase modulation, with broad skirts created by an amplitude modulation. Moving toward the accumulation parameter, at each bifurcation the total noise power decreases by a factor of 10.48, the average peak width decreases by a factor of 20.96, and the spectral bandwidth of the skirts decreases by a factor of 2.

• Received 19 January 1981

DOI:https://doi.org/10.1103/PhysRevLett.47.179